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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 01, January 2019, pp. 612–625, Article ID: IJMET_10_01_062
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=1
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
Scopus Indexed
COMPARATIVE AND EXPERIMENTAL STUDY
ON THE PROPERTIES AND POTENCY OF
SYNTHESIZED ORGANIC AND MINERAL
SUNSCREEN MOISTURIZER
*Oyinlola
R. Obanla, Modupe E. Ojewumi, Ayodeji A. Ayoola, Oladele J. Omodara,
Funmi Y. Falope and Olaitan H. Gbadamosi
*
Department of Chemical Engineering, Covenant University, Ogun State, Nigeria.
Department of Chemical and Food Sciences, Bells University of Technology, Nigeria
*Corresponding Author
ABSTRACT
This research work aims at synthesizing two different types of moisturizers: a body
butter and a lotion. Based on the methodology, three samples of the body butter and
lotion was produced, by varying the percentage of zinc oxide and Shea butter, the
samples were analyzed with a UV- spectrophotometer to determine the transmittance
and absorbance strength which was in turn used to determine the SPF. Vaseline which
is a standard organic lotion was also analyzed to determine the transmittance,
absorbance strength and SPF. The results were compared. Of all the moisturizers
synthesized in this research, the lotion which had 10% zinc oxide had the highest
absorbance strength, and hence the highest SPF. Therefore, it was concluded that a
minimum of 10% zinc oxide should be used in the production of sunscreen moisturizers
to provide moderate sun protection.
Keywords: Absorbance Strength, Body Butter, Lotion, transmittance, Sun Protection
Factor (SPF)
Cite this Article: Oyinlola R. Obanla, Modupe E. Ojewumi, Ayodeji A. Ayoola,
Oladele J. Omodara, Funmi Y. Falope and Olaitan H. Gbadamosi, Comparative and
Experimental Study on the Properties and Potency of Synthesized Organic and Mineral
Sunscreen Moisturizer, International Journal of Mechanical Engineering and
Technology, 10(01), 2019, pp. 612–625.
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612
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Comparative and Experimental Study on The Properties and Potency of Synthesized Organic
and Mineral Sunscreen Moisturizer
1. INTRODUCTION
The ancient Greeks used olive oil to protect the skin from sun damage. Over the years, the South
Americans use rice jasmine and lupine plants extracts by, as skin care to help protects their skin
from sun damage [6]. Sunscreen, otherwise called sunblock, is a gel like moisturizer that
absorbs, reflects, or scatters a portion of the sun's (UV) radiation and subsequently prevent
sunburn. The first sunscreen moisturizer ever known was produced in France by Eugene sculler
in 1935. In 1946, sunscreen produced by Franz Greiter was commercially introduced into the
market [16]. Schulze was credited with introducing the idea of SPF in 1956, thereby
approximately estimating the effectiveness of sunscreen when applied to the skin evenly at
3mg/cm2, and the first Greiter's cream was appraised later to have SPF of 2. However,
sunscreens have become a very essential skincare product worldwide. In 1990, $525 million
was spent on sun protection products in USA and the figure increased yearly [14] in a bid to
reduce the damaging effect of the (UV) radiation on the skin, [1and 4] reports that solar
radiation is the combination of visible light and ultraviolet radiation that reaches the earth from
the sun. A small portion of this spectrum is composed of short-wave length in the region 200nm400nm high energy ultra violet (UV) radiation harmful to life on earth. [17]. The application of
sunscreen prevents the absorption of UV radiation thereby reducing skin photo-damage and the
carcinogenic effects of solar irradiation [9 and 15]. There are two types of sunscreens actives
in use today: Organic sunscreen and Mineral based sunscreen. Both the organic and mineral
based sunscreens contain UV-filters. UV- filters are compounds or mixtures that block or
absorb ultraviolet (UV) light. [10 and 13]
1.1. Organic Sunscreen
These are known to as chemical filters. They are mostly aromatic compounds conjugated with
C=C double bonds, which have the electronic excitation energy in the UV range [10,15]. This
general structure allows the molecule to absorb high-energy UV rays and give out lower-energy
rays, which in turn prevents UV rays from getting to the skin [8]. Organic UV filters are made
up different classes (functional groups), which can be classified as UVA filters (benzophenones,
anthranilates and dibenzoylmethanes) and/or UVB filters (PABA derivatives, salicylates,
camphor derivatives and cinnamates) according to their specific absorption characteristics [18].
1.2. Mineral Sunscreen
Mineral sunscreens are made with inorganic UV filters. The most common types are TiO2 and
ZnO particles [15]. A maximum concentration of 25% UV filter are widely used in sunscreen
lotions as active broadband sunscreens that blocks both UVB (260–350 nm) and UVA (300–
450 nm) sunlight radiation with high SPF. Microfine particles, which make physical sunscreens
virtually invisible have been developed [3]. They are transparent to visible radiation, reflection
from the particle surface is minimal, and occasionally (TiO2 and ZnO) absorption are
maximized.
1.3. Testing of Sunscreen Products
Sun protection factor (SPF) is a measure of quantity of UV radiation required to produce
sunburn on protected skin (i.e. in the presence of sunscreen) [19]. As SPF value increases,
sunburn protection increases.
i.
There are two methods of measuring the sun protection factors:
(i) In vivo method: In this method, SPF is measured on human by applying 2 mg/cm2 of a
sunscreen formula to a portion on the skin, allowing dryness for 10minutes, and
administering a series of five increasing doses of UV radiation, to skin sites treated with
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Oyinlola R. Obanla, Modupe E. Ojewumi, Ayodeji A. Ayoola, Oladele J. Omodara,
Funmi Y. Falope and Olaitan H. Gbadamosi
the sunscreen. After 15hours, the irradiated skin sites are examined for SPF. The SPF is the
lowest dose of UV that causes mild sunburn in the sunscreen area divided by the lowest
dose of UV that causes mild sunburn in the area without sunscreen [5].
(ii) In vitro method: This method is cost-effective and rapid. It can be used as a formulation
tool to identify new filters and optimize combinations of old ones. This method is of two
types:
i.
the measurement of absorption of UV radiation through sunscreen product films in
quartz plates.
ii. the absorption characteristics of the sunscreens based on spectrophotometric
analysis of solutions [2, 12 and 18].
2. CREATIVE METHODOLOGY
Stearic Acid, Ethanol (99.5%), Zinc oxide obtained from Drug House (DBH), Poole, England,
Carrot seed oil (Daucus Carota), Red raspberry seed oil (Rubus Idaeus), Vitamin E oil (αtocapherol), Almond oil (Prunus Dulcis), Beeswax (Cera Alba), Coconut oil (Copra oil),
Jojoba oil (Simmondsia Chinensis), Shea butter (Vitellaria Paradoxa), Lavender oil (Lavandula
Angustifolia), Glycerine, and Emulsifying wax all obtained from Amazons in United States.
2.1. Preparation of Body Butter
A known quantity of water is heated in a double boiler to a temperature of 90oC. Plants’ flowers,
roots, leaves and seeds contain some active ingredients which are known as base or Essential
oil [11]. The base oils used in this study consist of 35% Coconut seed oil, 15% Almond seed
oil, 5% Jojoba seed oil and 22% of Shea butter are added to the upper portion of the double
boiler. The mixture is stirred continuously for 10 minutes.
Figure 2.1 Blending of the base oils over a double boiler
2.2 Blending of the Viscosifier, antioxidants and zinc oxide
4% of melted beeswax was added to the base oil in the double boiler, the mixture is stirred
continuously and allowed to cool to 40oC, 10% of zinc oxide was added and whisked for 15
minutes. 1% of the antioxidant and essential oils comprising of carrot seed oil (Daucus Carota),
red raspberry seed oil (Rubus Idaeus) were added to the mixture. The sunscreen moisturizer
produced is poured into a container and left to cool completely.
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Figure 2.2 Melted beeswax pellets
2.3. Production of different samples with varied Percentages of Zinc Oxide
The procedure above is repeated with varying percentages of zinc oxide with Shea butter to
produce three different samples.
(i) 2.3a Sample 2
• 23.5% of Shea butter is used in the production of the base oils.
• 7.5 % of Zinc oxide is added to the mixture
(ii) 2.3b Sample 3
• 25% of Shea butter is used in the production of the base oils.
• 5% of Zinc oxide is added to the mixture
2.4. Preparation of Lotion
4% of emulsifying wax is melted completely, 50% of zinc oxide was dispersed in 46% of jojoba
oil, and Zinc Oxide is blended with the melted emulsifying wax. 2% of beeswax emulsifying
wax are melted completely, 1.5% jojoba oil, 1.5% almond oil and 2% coconut oil are blended
together, the melted waxes are mixed with the oil. 68.7% of distilled water is added to 4%
glycerin and heated to 70oC, the mixture is stirred continuously for 20 minutes, and 0.5%
vitamin E oil, red raspberry oil, coconut oil, fragrance and 1% protein preservative are added
to the mixture at 40oC and allowed to cool.
3. RESULT AND DISCUSSION
The (SPF) is obtained using “in vitro” analysis with a UV-Spectrometer
i.
The absorption of samples in the solution were obtained using a 1cm quartz cell and
ethanol as a blank which was in the range of 280 to 470nm.
ii. The absorption data were obtained in the range of 290 to 320nm, every 5nm, and
three determinations were made at each point followed by the application of
Manseur equation.
Sample 1: Vaseline
Table 1 Spectrometric Analysis of dilute Sunscreen Solution
Ii x ee(𝞴)
Wavelength(nm) Absorbance(𝞴) Transmittance Ee x ii x abs (𝞴)
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0.015
290
0.104
78.70%
0.00156
0.0817
295
0.107
78%
0.0087419
0.28817
300
0.112
77%
0.032275
0.3278
305
0.107
78%
0.0350746
0.1864
310
0.105
79%
0.019572
0.0839
315
0.102
79%
0.0085578
0.018
320
0.091
81%
0.001638
Calculated SPF= 10.1
0.12
ABSORBANCE
0.1
0.08
0.06
0.04
0.02
0
285
290
295
300
305
310
315
320
325
320
325
WAVELENGTH
Figure 3.1 Absorbance against wavelength
81.50%
81.00%
TRANSMITTANCE
80.50%
80.00%
79.50%
79.00%
78.50%
78.00%
77.50%
77.00%
76.50%
285
290
295
300
305
310
315
WAVELENGHT
Figure 3.2 Transmittance against wavelength
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81.50%
81.00%
ABSORBANCE
80.50%
80.00%
79.50%
79.00%
78.50%
78.00%
77.50%
77.00%
76.50%
0
0.02
0.04
0.06
0.08
0.1
0.12
TRANSMITTANCE
Figure 3.3 Absorbance against transmittance
SAMPLE 2: Body butter containing 10 % Zinc Oxide
Table 2 Spectrometric Analysis of Dilute Sunscreen Solution
Ii x ee(𝞴)
Wavelength(nm)
Absorbance(𝞴)
Transmittance
Ee x ii x abs (𝞴)
0.015
290
0.063
86.50%
0.000945
0.0817
295
0.067
85.70%
0.0054739
0.28817
300
0.072
84.70%
0.02074824
0.3278
305
0.076
83.90%
0.0249128
0.1864
310
0.07
85.11%
0.013048
0.0839
315
0.063
86.50%
0.0052857
0.018
320
0.052
88.70%
0.000936
Calculated SPF = 7.1
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Funmi Y. Falope and Olaitan H. Gbadamosi
0.08
0.07
ABSORBANCE
0.06
0.05
0.04
0.03
0.02
0.01
0
285
290
295
300
305
310
315
320
325
WAVELENGTH(m)
Figure 3.4 Absorbance against wavelength
89.00%
TRANSMITTANCE
88.00%
87.00%
86.00%
85.00%
84.00%
83.00%
285
290
295
300
305
310
315
320
325
WAVELENGTH
Figure 3.5 Transmittance against wavelength
SAMPLE 3: Body Butter Containing 7.5% Zinc Oxide
Table 3 Spectrometric analysis of Dilute Sunscreen Solution
Ii x ee(𝞴)
Wavelength(nm)
Absorbance(𝞴)
Transmittance
Ee x ii x abs (𝞴)
0.015
290
0.051
88.90%
0.000765
0.0817
295
0.053
88.50%
0.0043301
0.28817
300
0.055
88.10%
0.0158494
0.3278
305
0.063
86.50%
0.0206514
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0.1864
310
0.057
87.70%
0.0106248
0.0839
315
0.039
91.40%
0.0032721
0.018
320
0.036
92.04%
0.000648
Calculated SPF = 5.6
0.07
ABSORBANCE
0.06
0.05
0.04
0.03
0.02
0.01
0
285
290
295
300
305
310
315
320
325
WAVELENGTH
Figure 3.6 Absorbance against wavelength
93.00%
TRANSMITTANCE
92.00%
91.00%
90.00%
89.00%
88.00%
87.00%
86.00%
285
290
295
300
305
310
315
320
325
WAVELENGTH
Figure 3.7 Transmittance against wavelength
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SAMPLE 4: Body Butter Containing 5% Zinc Oxide
Table 4 Spectrometric Analysis of Dilute Sunscreen Solution
Ii X
Ee(𝞴)
Absorbance(𝞴)
Wavelength (Nm)
Transmittance
Ee X Ii X Abs (𝞴)
0.015
0.027
290
93.90%
0.000405
0.0817
0.032
295
93%
0.002614
0.28817
0.035
300
92.30%
0.010086
0.3278
0.04
305
91.20%
0.013112
0.1864
0.037
310
92%
0.006897
0.0839
0.035
315
92.30%
0.002937
0.018
0.023
320
94.80%
0.000414
Calculated SPF = 3.6
0.045
0.04
ABSORBANCE
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
285
290
295
300
305
310
315
320
325
WAVELENGTH
Figure 3.8 Absorbance against wavelength
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95.00%
TRANSMITTANCE
94.50%
94.00%
93.50%
93.00%
92.50%
92.00%
91.50%
91.00%
285
290
295
300
305
310
315
320
325
WAVELENGTH
Figure 3.9 Transmittance against wavelength
SAMPLE 5: Body Lotion Containing 10% Zinc Oxide
Table 5 Spectrometric Analysis of Dilute Sunscreen Solution
Ii X
Ee(𝞴)
Wavelength (Nm)
Absorbance(𝞴)
Transmittance
Ee X Ii X Abs (𝞴)
0.015
290
0.072
84.70%
0.00108
0.0817
295
0.075
84.10%
0.006128
0.28817
300
0.078
83.60%
0.022477
0.3278
305
0.085
82.20%
0.027863
0.1864
310
0.082
82.80%
0.015285
0.0839
315
0.073
84.50%
0.006125
0.018
320
0.057
87.70%
0.001026
Calculated SPF = 8.1
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0.09
0.08
ABSOSRBANCE ()
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
285
290
295
300
305
310
315
320
325
WAVELENGTH (nm)
Figure 3.10 Absorbance against wavelength
88.00%
TRANSMITTANCE()
87.00%
86.00%
85.00%
84.00%
83.00%
82.00%
81.00%
285
290
295
300
305
310
315
320
325
WAVELENGHT ()
Figure 3.11 Transmittance against wavelength
Table 6 Summary of Absorbance Strength at Different Wavelength
ABSORBANCE
Wavelength
Sample 1
(Vaseline)
Sample 2
Sample 3
Sample 4
Sample 5
290
0.104
0.063
0.051
0.027
0.072
295
0.107
0.067
0.053
0.032
0.075
300
0.112
0.072
0.055
0.035
0.078
305
0.107
0.076
0.063
0.04
0.085
310
0.105
0.07
0.057
0.037
0.082
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315
0.102
0.063
0.039
0.035
0.073
320
0.091
0.052
0.036
0.023
0.057
0.12
0.1
0.08
Vaseline
Body butter(10%)
0.06
Body butter(7.5%)
0.04
Body butter(5%)
0.02
Lotion(10%)
0
Figure 3.12 Comparison of the absorbance strength of samples at different wavelength
The result obtained from this research work, shows that the absorbance increased as the
wave length increases from 290nm, at 305nm the absorbance value began to reduce. The
absorbance values at different wavelengths between 290nm-3210nm with 5nm interval was
obtained for each of sample. The standard Vaseline lotion with an organic UV filter had the
highest absorption values among all sunscreens tested. Of all the sunscreens creams synthesized
for this research work, with mineral UV filters sample 4, lotion containing 10% of zinc oxide
had the highest absorption values for the different wavelength. Sample 1, a body butter
containing 10% zinc oxide had the second highest absorption range, this was followed by
sample 2 which contained 7.5% of Zinc Oxide and sample 3 which contained 5% Zinc oxide.
The results show that increasing the quantity of the UV filter increased the absorption strength
of the sunscreen. It was observed that sample 1 and sample 4 which contained the same quantity
of zinc oxide had different absorption values, the difference was due to the variation in the
production method. The transmittance, which is the measure of amount of light radiation
allowed to pass through the solution of the different samples were determined through the UV
spectrophotometer and the values obtained were observed to be inversely proportional to the
absorbance. The graphs obtained from the results shows that transmittance is not linearly
proportional to the SPF. Despite its relationship with the SPF, it provides quantitative
information on the percentage of UVB rays filtered out by the sunscreen. The higher the SPF,
the lower the transmittance which meant more light absorbed by the sunscreen as also reported
by [5]. It was observed that the Vaseline had the highest absorption range and the lowest
transmission range among all the sunscreens tested. The transmittance range of sample 4 was
less than that of sample 1 which was in turn less those of sample 2 and 3 respectively.
Comparing the absorption and transmission range of the tested sunscreens it can be observed
that they are both inversely proportional because as the absorption increased the percentage
transmission reduced. This shows that the more UV- light is absorbed the less is transmitted to
the skin. Therefore, UV filters with high absorption characteristics are the preferred choice
when formulating a product. Vaseline lotion which is a standard organic UV filter having Butyl
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Methoxydibenzonylmethane and methoxycinnamate as the active UV filter, was tested through
in vitro method of analysis and SPF 10 was obtained and this was found to correlate with the
labeled SPF on the product. Therefore, this shows that the Vaseline lotion provides 90% of
UVB protection on the human skin. However, this result shows that the quantity of zinc oxide
increases as the SPF of the cream increases, but the final SPF is also a function of the particle
size and the quality when dealing with mineral UV filters.
4. CONCLUSION
The use of non- Nano Zinc oxide as a UV filter produces a sunscreen that provides moderate
sun protection. The quantity of zinc oxide used in production, determines the absorption
strength and hence the sun protection factor of the sunscreen. A minimum of 10% of Zinc oxide
should be used in formulations to provide moderate sun protection.
ACKNOWLEDGEMENT
Special thanks goes to all co- authors for their immense contribution, department of Chemical
Engineering Covenant University, Nigeria for their unfailing support throughout the course of
this research. The authors also appreciate the sponsorship by Covenant University.
AUTHOR’S CONTRIBUTIONS
Corresponding Author: Co-ordination of experimental work, editing, write- up.
Modupe E. Ojewumi: Checking the antiplaigairism and similarity test.
Ayodeji A. Ayoola: Soucing for more information, brainstorming.
Oladele J. Omodara: involved in experimental work and equipment handling.
Funmi Y. Falope: Funding for the research work.
Olaitan H. Gbadamosi: Sourcing for raw materials and reagents used.
ETHICS
This paper has neither been published nor submitted in any domestic or abroad journals.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Akinyemi, M. L. (2008): Dependence of UV-B Radiation on Ozone Concentration and
Solar Zenith Angle at Three African Stations. Nigerian Journal of Physics, 20 (2). ISSN
1595-0611 http://eprints.covenantuniversity.edu.ng/id/eprint/17822
Antoniou C.; Kosmadaki, M.G.; Stratigos, A.J.; Katsambas, A.D (2008). Sunscreens what’s
important to know J. Eur. Acad. Dermatol Venereol. v.22, n.9, p.1110- 1118.
Balaji A. B, Claussen A.H, Smith D.C, Visser S.N, Morales M.J, Perou R. (2007). Social
support networks and maternal mental health and well-being. J Women’s Health (Larchmt).
16 (10):1386-96.
Bens G., (2008). “Sunscreens. In: Sunlight, Vitamin D and Skin Cancer”, Ed. Reichrath J.,
Chap12, 137–161. Springer-Verlag.
Dutra E. A, Oliveira D. A, Kedor-Hackmann E. R, Santoro M. I (2004). Determination of
Sun Protection Factor (SPF) of sunscreens by ultraviolet spectrophotometry. Braz J Pharma
Sci.; 40: 381–5.
González-Arjona (2015).: “Study of Sunscreen Lotions, a Modular Chemistry Project”
Kiss, B.; Bíró, T.; Czifra, G.; Tóth, B.; Kertész, Z.; Szikszai, Z.; Kiss, A.Z.; Juhászl, I.;
Zouboulis, C.C.; Hunyadi, J. (2008) Investigation of micronized titanium dioxide
http://www.iaeme.com/IJMET/index.asp
624
[email protected]
Comparative and Experimental Study on The Properties and Potency of Synthesized Organic
and Mineral Sunscreen Moisturizer
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
penetration in human skin xenografts and its effect on cellular functions of human skinderived cells. Exp. Dermatol., Vol.17, n.8, p.659-667.
Lademann J, Schanzer S, Jacobi U, et al (2005). Synergy effects between organic and
inorganic UV filters in sunscreens. J Biomed Opt.
Lim, Henry W.; et al., eds. (2007). Photodermatology. CRC Press. p. 6.
Mbindyo J.K.N. and Brown A.K., (2010). “Investigating UV-Blocking Properties of
Sunscreens on the Microscale”, J. Chem. Edu., 87, 1388.
Modupe Elizabeth Ojewumi, Samuel Oluwafunsho Adedokun, Ayodeji Ayodele Ayoola,
Olugbenga Samson Taiwo (2018): Evaluation of the oil Extract from Mentha spicata and
its
Chemical Constituents. eprints.covenantuniversity.edu.ng/11143/1/revised%20paper.pdf
Pissavini, M.; Ferrero, L.; Alaro, V.; Heinrich, U.; Tronnier, H.; Kockott, D.; Lutz, D.;
Tournier, V.; Zambonin, M.; Meloni, M. (2003). Determination of the in vitro SPF. Cosmet.
Toiletries, Oak Park, V. 118, p. 63-72
Rigel, Darrell S. (2007). Photoaging. Hoboken: Informa Healthcare. pp. 73–74
Kenet O. Robert, Thomas B. Fitzpatrick (1994). Reducing Mortality and Morbidity of
Cutaneous Melanoma: A Six Year Plan: B) Identifying High and Low Risk Pigmented
Lesions
Using
Epiluminescence
Microscopy:
https://doi.org/10.1111/j.13468138.1994.tb03306.x
Sayre R. M, Killias N and Roberts R. L (1990). Physical sunscreens. J Soc Cosmet Chem.;
41: 103–109.
Shaath, Nadim A., Editor (2005). Sunscreens: Regulations and Commercial Development,
Third Edition. Taylor & Francis Group
Usikalu M. R, Omotosho T. V, Ndubuisi A. O., Achuka, J. A, Abodunrin T. J and Bello T
(2018): Ultraviolet Radiation Index over Ota, Nigeria. International Journal of Engineering
& Technology, 7 (4.5) 210-212
Walters, C.; Keeney, A.; Wigal, C. T.; Johnstom, C. R.; Cornelius, R. D. (1997). The
spectrophotometric analysis and modeling of sunscreens. J. Chem. Educ., Washington, v.
74, p. 99-102.
Wolverton S. E, Levy S. B. Comprehensive Dermatologic Drug Therapy. 2nd ed. 2007; 38:
704–708.
http://www.iaeme.com/IJMET/index.asp
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